Electrical piano.



R. A. ROSE & G. G. HOLBEOOK.

ELECTRICAL PIANO.

APPLICATION FILED MAR. 29, 1909.

962,261 V Patented June 21, 1910.

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WlTN ESSES INVENTORS ATTORNEY Aida;

UNITED STATES PATENT OFFICE.

ROBERT A. BOSE .A'ND GEORGE. G. HOL BILOOK, OF SANTA ROSA, CALIFORNIA.

ELECTRICAL PIANO.

Specification of Letters Patent. Patented June 21, 1910.

Application filed larch 29, 1909. Serial No. 486,394.

the following is a specification.

. reci rocate The present invention relates to electrical pianos, the object of the invention being to provide improved electric means for actuating and controlling the hammers and dampers of the piano.

The invention resides in the novel construction and arrangement of parts hereinafter described and more specifically pointed out in the claims. i

In the accompanying drawing, Figure 1 is a vertical transverse section of the upper portion of a piano equipped with our invention, certain parts bein shown dia ammatically; Fi 2 is an en arged detail sectional v1ew o the ke mechanism; Fi 3 is an enlarged vertic section throug the magnets.

Referring to the drawings, 1 indicates the usual case containing the sounding board 2, the string plate 3, the tuning pins 4 and the strings 5.-

Hammer magneta+The hammer magnets are formed of two coils 6 wound on nonmagnetic tubes 7, fastened at the outer ends to a non-magnetic oke 8, the latter being secured to a brass p ate 9, and at their inner ends to a magnetlc yoke or stay 10. To said stay 10 is also secured between: the tubes 7,.

the inner end of a guide tube 11, preferabl of brass, its outer end projecting throu the outer yoke 8 and into an o emng in t e brass plate 9. Within said tu s 7 and 11 lungers 12, 13, the two lungers 12 ing '0 magnetic material, w ile' the plunger 13 may be ma etic or non-magnetic, as convenient. T e plungers, 12 13, are secured to a magnetic yoke 14, which reci rocates freel u onguide rods 15, and sai plungers an yoke are normally pressed outward or coiled around the tube 11. In the inner ends of the tubes 7 and 11 are plun rs 17, 18,

' I connected to a non-magnetic yo e 19, u on tac w which is mounted a hammer 20 adapt'e' to strike the piano'strmgs' 5, The outer gers 17 are of magnetic material and 0 such the when the hammer 20 is in conspring 33 within forward'by a coiled spring 16.

' single iece of brass 9 so e the front ends of saidplungers will be just within the helical coils 6. The plunger 18 is of non-magnetic ma-- terial and of such length that, when it is in its outermost or forward position, the plunger 13 being in its innermost osition, there is a space of about one-eight of an inch between them, thus permitting the hammer to rebound from the string and to be held inits retracted position by the pull of the electro-magnet.

The operation of the hammer magnets is i as follows: Upon the circuit of any note being closed, the plungers 12 are drawn into the helices, as are also the plungers 17, 18, should they, as shown in Fi s. 1 and 3, not have been completely with rawn thereinto, as after playing a note staccato, and the plunger 13 will strike the plunger 18, and cause the hammer to be projected against the string. Upon rebounding, the hammer will be held in its retracted position so. long as the circuit remains closed. Upon the circuit being opened, the spring 16 will cause the plunger 13 and yoke 14 to resume a osition ready for another stroke. amper magnets.The damper magnets comprise ma netic tubes 22, secured at their outer en s to a magnetic yoke 23 mounted on the brass plate 9, and within which tubes for a portion of their length are the magnetic cores 24. The inner ends of the tubes 22 are held in place by a non-magnetic yoke 25. Between these coils, and passing through both okes 23 and 25 is a tube 26, having at its outer or front end an adjustingscrew 27. Within the tubes 22 and 26 reciprocate the magnetic plunger 28 and non-magnetic plunger 29, mounted on a yoke 30 of magnetic material, which also carries a dam er 31 and is guided by rods 32. A 00] ed the tube, 26 holds the damper against the string 5 until the circuit is closed, when the damper-1s drawn away from the string by the electro-magnets.

Sustaining nets consist' o the magnetic cores 34 screwed into a magnetic oke 35, aroun said cores bein wound the e ectri'cal coils 86. All of tire 'nt 'yokes, for (phe htammer m ets, am r magnets, an sus ammg fiets for e hinote, are secured to the as to be readily removab e, all of said 9 being secured to upper and lower longitudinal bars 37 38.

two helical coils 21, wound on nonmite-The sustaining magin said guide piece and finger ger 50 of magnetic materia K ey mec'hanism.-42 indicates a finger key of the iano, its rear portion being sufiiciently t in as to be resilient, and secured at the rear end upon asuitable longitudinal base 43. Said finger key is normally pressed upward by means of a spring 44 coiled around a guidestem 45. Pads of felt 47 are,

suitabl located to receive the impact .of the finger ey when itis depressed.

48 indicates a block secured to the under side of the finger key, and, in a socket 49 key, is a plun- The lower end of said plunger is, in the normal position of the finger key, adjacent to a permanent magnet 51, and near said lower end, said plunger carries a conical contact collar 52, which is adapted, when the lunger is depressed, to contact with, and e eotrically connect, two contacts 53, 54. The contact 53 is connected by a wire.5 5 with a post 56, along which slides a metallic arm 57 carried by the block 48, the end of said arm sliding over a coil 58 of high resistance wire wound around posts 59 on the frame. The other endof said coil 58 is connected by a wire 60 with the sustaining magnets36, the damper magnets21, and the hammer magnets 6 in parallel. The contact 54 connects by a wire 130 through a battery 68 and switch 71 with the center of a rotating circuit breaker 61 rotating on a shaft 77, the periphery of which is divided into a suitable number of contacts 62 separated by insulatin portions 63. Said circult-breaker is rotate under a brush 64, which is connected by a wire 67 to the sustaining magnets 36. Branch wires69, 70, the former controlled by a switch 71 lead to the damper and hammer magnets.

To avoid sparking between the lower end of the plun er and the contacts 53, 54, which woul very quickly im air the efliciency of the iano action, t e followin provlsion is ma e. The plunger is provided with a collar 74 rigidly secured thereto, and around the plun r, on opposite sides of said collar, and within the recess formed in the I block, are two coiled springs 75, 76 of the same strength. Theses rings act in opposite directions, and tend ways'to center the collar within the socket, and they have the effect of making a quick acting break between the plunger and its contacts. Thus,

when the key has been depressed so that the lower end of the plunger approaches 'near enough to the permanent magnet to be moved thereby against the action of the lower spring 7 6, the magnetism of said magnet overcomin the action. of the spring makes a uic connection between the plunger an magnet;v On the other hand, when the key is effect is, first,'to

compress the lower spring, the plunger remaining still in contact with -t e m net, until saidsprin has been compresse to such an extent t at its pressure overcomes the attraction of the magnet, whereupon the net and from the contacts 53, 54.

We claim 1. In an apparatus of the character'described, the combination with strings, of hammers therefor, and eleotro-magnets for propelling said hammers against the strings, and for withdrawin the same therefrom, substantially as described.

2. In an apparatus of the character described, the combination with strings, of hammers having parts attached thereto solenoids, cores attached to the hammers an arranged to be attracted by the solenoids, and cores arranged to be attracted by the solenoids in the opposite direction to the firstmentioned cores, and, when so attracted, to impinge u on the parts attached to the hammers, an prope the latter against the strings, substantially as described.

3. n an apparatus of the'character described, the combination with strings, of hammers having parts attached thereto, solenoids, cores attached to the hammers and arranged to be attracted by the solenoids, and cores arranged to be attracted by the solenoids in. the opposite direction'to the first-mentioned cores, and, when so attracted, to impingeupon the partsattached to the hammers, and propel the latter against the strings, and sprmgs for returning the propelling cores to their normal position, substantially as described, 4

4..In an apparatus of the character described, the combination, with strin of hammers having parts attached thereto solenoids arranged at right an les to said strings and immediately behind the hammers, frames carrying said solenoids, and provided with means for guidin the hammers to and from the strings an in a direction at ri ht an lea-thereto, cores in said solenoids etache from the hammers, and

.to cause them to impinge upon said arts attached to the hammers, and prope the hammers against the strings, and s rings for withdrawing the cores, substantm y as described. I

In testimony whereof we have hereunto set ourhands in thepresence of two subscribingwitnesses. ROBERT-A. ROSE. GEORGE G.- HOLBROOK.v -W e;" Fnan'ors M wmomr,

t 3431mm.

plunger makes a quick break from ,the'magsolenoids being arranged to attract said cores 

